[rrd-developers] Accelerator Daemon

Florian Forster rrdtool at nospam.verplant.org
Tue Jul 15 20:57:11 CEST 2008

Hi again,

as before, the newest patch is available from

On Fri, Jul 04, 2008 at 03:07:37PM +0200, Tobias Oetiker wrote:
> I would like to see that all the functions which read from an rrd file
> will flush the daemon prior to reading 

I've spent quite some more time adding support for the daemon to most
``commands''. The commands aware of the daemon now are:

All but `update' send a `FLUSH' command before reading the file.
`update', of course, sends an `UPDATE' command.

So this leaves the following commands without a `--daemon' option:

I've added a new command, `flush'. This command does nothing but connect
to the daemon, flush one file and disconnect again.

> ... and that the updatev function would flush,lock,update,unlock

Sorry, but that simply leads the hole concept ad absurdum. Besides,
there is no guarantee that the file is written after the flush command
returns (it's very very likely, though). So have an ugly race condition
there. Last but not least: If two sources update the same RRD file, your
layout is seriously broken.

> the motivation for this is, that existing systems can use a daemon
> based setup transparently.

People who rely on `updatev' should not use the daemon. Transparently as
thin air.

I have to admit that I'm losing interest in this, because I have the
impression that besides me no one really cares and I have tons of other
stuff to do. So if someone finds a bug or has a ``real'' issue, I'm
happy to do that. If you think that `resize' and `tune' should flush the
file, too, please do it yourself. If you care enough, that is.

Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
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